Components (shaped parts), in which hardened cement paste, whose constituents include C—S—H phases, assume the function of a binding agent, are typically produced in three steps:                1. The starting materials cement, aggregates and water are mixed (so-called tempering).        2. This mixture, which is described as cement paste, fresh mortar or fresh concrete, is poured into a mold and mostly mechanically vibration-compacted.        3. The component cures for a length of time until the surrounding mold can be removed.        
It is important in this context that the composition of the mixture be such that a suitable consistency during processing and a long enough workability are ensured. In the same way, the composition of the mixture or the curing thereof must be such that, once the reaction with water has taken its course, the requisite final strength is obtained.
The three mentioned steps are carried out in cement-containing systems by a coordinated reaction of the cement constituents. CEM I (Portland cement) includes a mixture of two groups of minerals, which each perform a function:                1. calcium silicates, whose hydration products are responsible for the final strength of the shaped part; and        2. calcium aluminates, calcium aluminate ferrates and calcium sulfates, which control the workability and the early strength.        
In addition, other inorganic and organic substances can be added, for example, to compact the structure, improve workability or enhance strength.
The following disadvantages are associated with the described approach:                Producing cement-containing binding agents requires high temperatures (for example, 1450° C. for CEM I), thereby entailing high energy costs.        Only some of the phases which build up the binding agent (approximately 50% for CEM 1, for instance) contribute to the final strength of the component.        Approximately 50% of the calcium carbonate used to produce CEM 1 is neutralized in a process that entails considerable expenditure of energy and that does not contribute to the later strength in the component. This pollutes the environment with CO2 emissions.        To obtain the requisite reactivity for the product, the cement calcination is followed by a grinding process that is costly in terms of energy usage.        Calculating the mixture proportions is a complex process that is based on experience. Variations in raw material qualities make it necessary to constantly adjust the mixture proportions.        Special additives used in the mixtures are expensive.        Only a precisely defined period of time is available for the processing. Interrupting the processing is only possible to a very limited extent.        The strength of the mixture increases following the processing thereof only over a long period of time.        The chemical properties of the phases formed during mixing vary and, therefore, are not able to be optimally adapted to the aggregates used.        It often takes months before the final strength is reached.        The final strength is reduced by a high porosity, a low particle-to-particle bonding, and by a reduction in the proportion of strength-determining phases.        The shaped parts have limited stability under external chemical attack, for example by acids, CO2, or sulfates.        
S. Goni, A. Guerrero, M. P. Luxan and A. Macias, Activation of the Fly Ash Pozzolanic Reaction by Hydrothermal Conditions, Cement and Concrete Research 33, pp. 1399-1405, 2003 describes producing low-calcium fly ash belite cement from fly ash using a two-step process. To this end, a hydrothermal treatment of the fly ash is first carried out under saturated water-vapor partial pressure at 200° C., and a calcination is subsequently performed at 700° C. Following preparation, the fly ash belite cement is tempered with water and processed in a conventional manner. The energy costs are significantly reduced in comparison to the production of Portland cement, however, the process requires neutralizing a higher proportion of CaCO3 than during production of the strength-determining phase, thereby additionally polluting the environment with CO2. Only some of the phases which build up the binding agent contribute to the final strength of the component since fly ash belite cement contains calcium aluminates and calcium aluminum ferrates, in the same way as CEM I. On the other hand, the grinding costs are lower than in the case of conventional CEM 1. Fly ash is available on only a limited basis and is comparatively expensive. Since fly ash belite cement is further processed in the conventional manner, it is not suited for overcoming the remaining disadvantages mentioned above.
In Synthesis, Moisture Resistance, Thermal, Chemical and SEM Analysis of Macro-Defect-Free (MDF) Cements, Journal of Thermal Analysis and Calorimetry 78, pp. 135-144, 2004, S. C. Mojumdar, B. Chowdhury, K. G. Varshnney and K. Mazanec discuss producing macro-defect-free cement (MDF) by blending various clinker materials, such as SAFB, CEM I or Al2O3, with other inorganic and organic additives. MDF cements are tempered in a conventional manner, but using a greatly reduced water/solid ratio, and processed.
G. R. Gouda and D. M. Roy, Characterization of Hot-Pressed Cement Pastes, Journal of the American Ceramic Society 59, pp. 412-414, 1976, and A. A. Paschenko, V. V. Chistyakov, E. A. Myasnikova and L. A. Kulik, Formation of the Structure of Hot-Pressed Cement Paste, Dopo-vidi Akademii Nauk Ukrainskoi RSR, Seriya B, Geologichni Khimichni ta Biologichni Nauki 9, p. 41 (abstract), 1990 both describe production of hot-pressed cement paste by curing cement pastes, which have been tempered with water and processed in the conventional manner, at an elevated pressure (3-5 kbar) and elevated temperature (150-250° C.).
Both the structure of the MDF cements, as well as of the hot-pressed cement pastes, is denser than that of conventional CEM I and does not include macropores. However, in the micrometer range, the primary porosity is considerable. The final strength is not obtained until after immersion in water and is greatly increased over CEM I (up to 700 N/mm2 in the case of hot-pressed cement pastes). The stability under external chemical attack, for example by acids, CO2 or sulfates, is improved over CEM I due to the denser structure. However, in the case of these products, there is the risk of so-called swelling due to unreacted clinker phases. Neither MDF cements nor hot-pressed cement pastes are capable of overcoming the other disadvantages enumerated above.
G. Mi, F. Saito and M. Hanada, Mechanochemical Synthesis of Tobermorite by Wet Grinding in a Planetary Ball Mill, Powder Technology, volume 93, pp. 77-81, 1997 describes production of the C—S—H phase tobermorite by what is termed the mechanochemical treatment of an aqueous suspension of CaO and SiO2 in an agate ball mill grinder.
The German Patent 28 32 125 C2 describes a method which provides for mixing CaO- and SiO2-containing materials with a synthetic calcium silicate (CaO:SiO2 ratio, in each case 0.8 to 1.1) and for working in fibers in the presence of water. Following a delay time of at least five hours (“pre-reaction”), a pumpable paste is formed since the sedimentation tendency is prevented by stirring, and the paste is poured into plate-shaped molds and dewatered under pressure. Following an autoclave curing and drying, “fire-resistant, dimensionally accurate lightweight building slabs” are obtained. The calcium silicate is synthetically derived and is produced by autoclave curing.
The German Patent Application DE 33 02 729 A1 describes the conversion of water-dispersed starting materials under heating and subsequent filter pressing (dewatering forming), subsequent steam curing and subsequent drying. The conversion (heating) takes place at a temperature of 80 to 230° C. within 30 minutes to 10 hours.